Description:This Handbook discusses various systems and the equipment (components or assemblies) they comprise, and describes features and differences. This information helps system designers and operators in selecting and using equipment. This edition includes a new Chapter 18, Variable-Refrigerant-Flow Systems, which describes these systems, their components, and applicable standards in detail, and includes a system design example and important guidance on costs, controls, and safety. This Handbook is a reference for engineers working in HVAC&R and for professionals in allied fields. ASHRAE, founded in 1894, is an international organization of some 50,000 persons. ASHRAE fulfills its mission of advancing heating, ventilation, air conditioning, and refrigeration to serve humanity and promote a sustainable world through research, standards writing, publishing, and continuing education.